Underreamer.



E. L. MILLS. UNQERREAMER. APPLICATION-ULEB AUG.29. l9l6.

Apr. l3, 1917.. 3 SHEETS-SHEET l.

Patented La# M.

E. L. MILLS.

UNDERREAMER.

APPLICATION FILED AUG.'29I I9I6. I

Patented Apr. 3, 1917.

3 SHEETS-SHEET 3 4 W Z m m 0. f m j I W., j I+! /nl I nr rc.

EDWARD L. MILLS, 0F LOS ANGELES, CALIFORNIA.

'UNDERREAMl-ER.

Specification of Letters Pat-ent.

Patented am. s, rait.

Application filed August 29, 1916. Serial No. 117,460.

4in construction, effective, reliable and durable in use and inexpensive and simple of manufacture.

The accomplishment of this object involves several novel features of construction, all of which I explain in detail in a preferred form in the following specification.

But before proceeding to this detailed speci lication, I may give a general description of the structural features of my underreainer.

In a preferred structure embodying my invention, I utilize a mandrel (which, as hereinafter explained, may be in a single piece) with a downwardly extending tongue at the lower end. rIhis tongue is of smaller size than the mandrel itself, so that there is formed at the lower end of the mandrel and at the top of the tongue a downwardly fao ing shoulder against which the upper ends of the cutters may bear when in their operative, expanded position. It is a feature of my invention that the cutters may entirely surround the tongue; that is, may entirely surround the tongue with the exception of the small space which must be left for their contraction. It is a distinction that the cutters are mounted around the tongue rather than in it or in a slotted extension of the mandrel; and this distinction carries .with it specific advantages, notably that the cut` ters extend over a very largepart of the total area of the bore hole. y

Another distinctive feature is that the tongue is solid; is not perforated or slotted, or provided with a central bore; neither is the mandrel provided with a central bore. The cutter elevating means are mounted in the mandrel in small lateral bores which are entirely exterior of the tongue; `and the cutter elevating means connects with the cutters entirely exterior of the tongue. In this manner, which is more specifically hereinn after pointed out, I maintain the greatest possible strength in that part of the reamer body which is usually thewea'kest.

The manner in which the cutters are mounted upon the tongue is also a distinctive feature, which is hereinafter described in detail; embodying the support of the cutters in such a manner as to hold them rigidly and strongly in place. In this connection it will` be borne in mind that the cutters in my reanier are external cutters rather than internal; that they fit around the tongue on the lower end of the mandrel rather than that they t within slots or the like in the mandrel body.

All these features, together with other distinctive features and features of detail are explained in the following specification wherein I describe a preferred embodiment of my invention, reference being had to the accompanying drawings, in which, for the purpose of this specification, I illustrate said prefered embodiment of my invention; In the drawings Figure l is a side elevation of my underreainer in expanded or operative position; Fig. 2 is a side elevation of the lower parts thereof, showing the parts contracted within a well casing; Fig. 3 is a longitudinal section as indicated by line 3-3 on Fig. l; Fig. 4 is a bottom view of the unw derreamer in its expanded position; Fig. 5 is a side elevation ofthe lower part of the mandrel and the tongue; Fig. 6 is a bottom view of the mandrel and tongue; Fig. 7 is a section taken as indicated by line 7-7 on Fig. 3, showing a vertical section of the cutters and their el vating device; Fig. 8 is an enlarged cross-section taken as indicated by line 8-8 on Fig. 3; Fig. 9 is a section taken as indicated by line 9-9 on Fig. 8; Fig. l0 'is an enlarged cross section as indicated by line 10-10 on Fig. 3; Fig. l1 is an enlarged cross section taken as indicated by lines 11--11 on Fig. 3 and on Fig. 7; Fig. 12 is an enlarged cross section taken as indicated by lines 19,-12 on Figs. 3 and 7; Fig. 13 is a perspective showing one form o f cutter; Fig. 14 is a view, similar to Fig. 7, showing another form of cutter; Fig. 15 is an inner face view of said form of cutter;

Fig. 16 is a side elevation of the form of mandrel tongue to accommodate the cutter of Fig. 14; Fig. 17 is another side View of said tongue; and Fig. 18 is a perspective showing the last mentioned form of cutter.

In the drawings the numeral 10 designates a mandrel which, according to my invention, may be, and preferably is, in one piece. The manner in which the cutter elevating and supporting bolts are mounted in and inserted in the mandrel makes it possible to use a one-piece mandrel; thus making the mandrel of the maximum strength. This mandrel is provided at its upper end with any usual arrangement for connection to a. string of drilling tools; and at its lower end it has a downwardly extending tongue 11. This tongue 11 ,is preferably of the configuration shown in the various views, having opposite, vertical, parallel bearing faces 12. These bearing faces 12 face outwardly and are two in number, (the number of cutters in this preferred construction being two. It will be understood, however, that the number of cutters may be two or more, as desired). At each of the opposite edges of the bearing faces 12, the tongue 11 has overhanging edge portions 13 whose inner faces form inwardly facing bearing faces 14 which face inwardly toward each other. At the lower end the tongue has a downward extension 15 with lower diagonal surfaces 16; and at the upper end'of the extension, at the lower end of the main part of the tongue, there are downwardly facing horizontal shoulders 17. At the lower end of the mandrel 10, and at the upper end of the tongue 11, there is a downwardly facing shoulder 18; and, as hereinafter explained, the cutters when in their operative or expanded position bear upwardly against the Y shoulders 17 and 1S.

Within the mandrel 10 I make a plurality of bores 20, their number depending upon the number of cutters, which in this case is two. Accordingly, there are two of these bores 20, situated opposite each other in the position shown, relative to the tongue 11. It will be noted that the bores are entirely exterior of the tongue; that is, that they are outside of the side surfaces or planes of the tongue, as is clearly shown in Figs. 3 and 6. The cutter supporting bolts 21 extend up into the bores. Bolts 21 are supported by compression springs 22, the upper ends of these springs pressing upwardly upon nuts 23 on the upper ends of the bolts and the lower ends 0f the springs resting upon sleeves 24, which surround the bolts and fit into the bores 20. Each of the sleeves 24 has a lug or projection 26 which fits into a way or groove 27 cut in the mandrel 10 as an extension of the bore 20. A wedge key 25 lies in a cross opening 28 through the mandrel and lies under the lugs 26, thus supporting the sleeves 24. At its forward end, this wedge key has an inclined face 29; and it also has two notches 30 into which the lugs 26 may settle down, thus preventing the accidental removal of the wedge key 25. The sleeves 24 rest upon enlargements 31 at the lower end of bolts 21 when the bolts are inserted in the mandrel. The sleeves 24 are thus originally a short distance below their normal position. When the wedge key 25 is inserted, its forward inclined face 29 is driven against and under the lugs 26 of sleeves 24 and causes them to be raised; the wedge key bein then driven through to position where the lugs 26 rest in the notches 30. The sleeves are thus raised oli' enlargements il] aud are then supported upon the wedge key 25. The sleeves then form stationary supports for the lower ends of coi'npression springs 22; and the springs then tend to lift the bolts 21 upwardly. The upward movement of the bolts is limited bv the upward nievement of the cutters to which the lower ends of the bolts are connected.

Each bolt has upon its lower end a rectangular head 35, each of which heads engages in notches 36 in the upper ends of the cutters 37. The cutters 37 surround the tongue 11, each of the cutters being rel cessed on the inner face, as illustrated, and as will hereinafter be described in detail' At their upper ends the cutters completely surround the tongue 11, as is shown in Figs. 1, 2 and 10. The points at which the cutters meet are directlv beneath the bolts 21 and the rectangular heads 35 each engage half in one cutter and half in the other. Each cutter is provided with two notches 86; and the edge of the bolt head 35 enters under the overhanging upper wall 36a of these notches. The bolt head fits freely in the notches so that the cutters may have the relative motions, hereinafter described` without binding upon the bolt heads; and yet the bolt heads lit the notches with sutlicient accuracy so that when one cutter moves vertically the other cutter will be caused to correspondinglv move through the medium of the bolt heads 35. It will be noted, particularly by reference to Fig. 7, that the points where the two opposite cutters connect with the bolt heads 35 are very close together; so that the bolt head forms a short and rigid connection between the two opposite cutters. This obviates the possibility of any binding or twisting` of the bolt head when one of the cutters is moved vertically.

Each of the cutters has a lower cutting or drilling end 40 and an exterior surface 41 adapted to engage the inner surface of the casing, as is shown in Fig. 2. The side surfaces of each cutter are preferably flat, as shown at 42; excepting that at the top of each cutter there is a portion whose exterior surface is practically semi-cylindrical, as is illustrated at 43.l 1t is at this point, the upper ends of the cutters, that thecutters completely surround the tongue 11 and meet cach other, or substantially meet each other, at their surfaces 44. When the cutters are in their expanded position, these surfaces bear against each other; and when the cutters are in their contracted position, as shown in Fig. 2, the surfaces 45, directly below the surfaces 44, are bearing against cach other. The line at a at the upper edges of surfaces 45, may be taken to represent the axis about which the cutters swing when expanding and contracting. rl`his may be readily seen by inspection of Figs. 2 and 7. Below the point represented by the line the cutters are of such configuration as to leave a space between them for the purpose of allowing their contraction. The cutters have inwardly facing opposite surfaces 47 which bear against each other when the cutters are contracted; and above these surfaces 47 there is a space adapted to accommodate a stop-pin 48. The downward movement of the cutters is limited by shoulders 49 moving down onto this stop-pin, set through the tongue 11.

Each of the cutters is recessed on its inner face, the recess being open at the upper and inner faces. This is clearly shown in Fig. 13. The back wall of the recess has an uppermost vertical surface 50 which bears against the surface 12 of the tongue 11 when the cutters are intheir expanded position; then an intermediate, downwardly and outwardly receding surface 51 which bears against the surface 12 of the tongue when the cutters are collapsed, as is shown in Fig. 2, the diagonal surface 52 below the surface 51 being then below the horizontal shoulder 17 of the tongue; and at its bottom this back wall of the recess has another vertical surface 53, in the same plane as surface 50, which vertical surface 53 bears against the lower part of surface 12 when the cutters are expanded. The bottom of the recess is formed by the horizontal surface 54 which bears upwardly against the lower horizontal shoulder 17 of the tongue when the cutters are expanded, and which lies below the lower diagonal surfaces 16 of the lower extension of the tongue when the critters are contracted. The recess has an overhanging front wall at each of its opposite sides, which overhanging front walls present a pair of inwardly facing surfaces 55, vertical and parallel to the back surfaces 50 and 53 of the recess. These surfaces 55 bear against the inwardly facing surfaces 14 of the tongue when the slips are expanded. The surfaces 55 extend upwardly to a point opposite the lower edge of the upper back vertical surface 50, and from that point upwardly they recede from the back surface 50, as is illustrated at 56. `When the cutters are in their compressed position, the surfaces 56 bear against the inward surfaces 14 of the tongue, as indicated in Fig. 2.

Below the horizontal surface 54 at the bottom of the recess there is a vertical inwardly facing surface 60 on the cutter which bears against the vertical face 61 of the tongue when the cutters are expanded. These surfaces G0, together with the lower vertical surfaces 53, constitute double spreading surfaces and support the lower end of the cutters against movement toward each other, and against the stress or force which tends to crush them toward each other. The bearing of the surfaces 55 (which surfaces may be termed rentrant surfaces) upon the inward surfaces 14 of the tongue, supports the cutters against outward movement. 1t will be noted that the surfaces 55 and 14 bear upon each other for a considerable vertical distance; throughout almost the whole vertical length of the recess; and it will be noted that the cutters have opposite bearing surfaces 50 and 53 spaced at the top and bottom of the recess; so that each cutter is firmly heldin position both against the stresses which tend to move it outwardly and stresses which tend .to move it inwardly.

The foregoing description applies fully to both the forms of tongues and cutters shown in the drawings; and I now explain the details in which these two forms differ.

'In the form of cutter' shown in Fig. 13 the recess bottom is square and the bottom surface is flat. A straight horizontal lip 30 projects across the bottom front of the recess in the form shown in Fig. 13; and this lip 8O projects up into undercuts 81 across the lower face 17 of the tongue. Or, the construction may be described by saying that the over-hanging edge portions 13 of the tongue extend on across the bottom at 17 and the under cuts 81 are formed between these bottom extensions of the overhanging portions 13. and the extension 15 of the tongue. And the lips 80 may be regarded as an extension of the overhanging front walls of the recess in the cutter, said lip 8O extending across the bottom front of the recess. Now, in the form shown in Figs. 14 to 18, the structure is essentially the same as in Fig. 13, etc., with the eXception that the bottom of the recess is curved as shown at 54a instead of being straight. The lip 30a is also curved, as is also the surface 52L of the back of the recess. The lower end of the tongue 11 is correspondingly rounded; and the fianges 17 a are formed as curved continuations of the overhanging edge portions 13 of the tongue. These flanges 17a form the downwardly facing shoulders of the tongue against which y terconnection between the cutters.

the recess bottoms 54a bear upwardly; and the curved lips Sila fit up behind the lianges 17, In this construction the lower end of tongue extension 15 is also rounded as shown in 16a so as to not cause mutilation of the curved parts 80L when they slide thereon when the cutters are contracted.

It will be seen that the construction just described materially strengthens and strongly supports the cutters against outward movement and keeps any excessively concentrated strain off the lower ends of the overhanging side portions 13 of the tongue.

Irovision for holding the cutters firmly against lateral motion is made by the bearing of the side surfaces 65 of the recess against the side surfaces GG of the tongue; and the bearing of surfaces 67, of the .front walls of the recess, against side surfaces GS of the tongue. Furthermore, it will be noted that at the sides of the vertical surface 16 there are small lateral surfaces 69 which bear against the side surfaces of the lower extension 15 of the tongue. These lateral surfaces 69 are not very large in extent; but they are situated low on the cutter, at a point close to the cutting end, and therefore materially aid in strongly supporting the lower ends of the cutte against lateral displacement;

As I have hereinbefore stated, it is one of the features of my reamer that the tongue is solid, and not weakened by bores, slots, or any of the usual openings therethrough. I obviate the weakening of the tongue by putting the cutter elevating means exterior of it; and by putting the cutter elevating means in this position I make it possible to insert said means in the mandrel from below. In underreamers of which I am aware the elevating means must be inserted from above; and this means that the mandrel bore must be carried upwardly through the pin 10a, seriously weakening this pin. My reamer -body is solid above the bores 20; and it will be seen that these bores do not extend above .the heavy and full-sectioned part of the mandrel. Making the cutters externalmaking them surround the tonguefacilitates connection to the elevating means situated laterally; and facilitates shortA innd making the cutters external also has many other advantageous features, as herein stated. It will be understood that by saying that the cutters surround the tongue I do not necessarily mean that they completely encircle it, but that the cutters surround the tongue rather than the mandrel surrounds the cuttersthe cutters are exterior with reference to the tongue rather than the mandrel being exterior with reference to the cutters.

I have described a preferred embodiment of my invention; but I do not consider my invention to be limited to the specific structure and details herein explained. Hthin the scope of the appended claims various changes in form and arrangement may be made without departing from my invention.

Having described a preferred form of my invention, I claim:

1. In an underreamer, the combination of a mandrel with a downwardly projecting tongue, recessed cutters vertically movable on and fitting around the tongue, and elevatingmeans in the mandrel exterior` of the tongue connecting with the` cutters and adapted to move the cutters up on the tongue.

2. In an underreamer, the combination of a mandrel having a downwardly proj ccting tongue, cutters vertically movable on and substantially entirely surrounding the tongue, and elevating means in the mandrel exterior of the tongue connecting with the cutters and adapted to move the cutters up on the tongue.

3. In an underreamer, the combination of a mandrel having a, downwardly projecting tongue with outwardly facing bearing faces and inwardly facing bearing faces, cutters vertically movable on the tongue substantially entirely surrounding the same and having surfaces bearing against said bearing faces of the tongue, and means to hold the cutters in their upper positions on the tongue.

4. In an underreamer, the combination of a mandrel having a downwardly projecting tongue with opposite outwardly facing bearing` faces and with opposite inwardly facing bearing faces formed by the inner surfaces of overhanging edge portions of the tongue, cutters vertically movable on the tongue substantia-lly entirelv surrounding the same and having spreading surfaces adapted to bear against the outward faces of the tongue and having rentrant outwardly facing surfaces bea-ring against the inward faces of the tongue, and means to hold the cutters in their upper positions on the tongue.

5. In an underreamer, the combination of a mandrel having a downwardly projecting tongue, cutters vertically movable on the tongue, said cutters being recessed on their inner faces to fit around the tongue, and the cutters collectively substantially entirely surrounding the tongue, and elevating means in the mandrel exterior of the tongue con` necting with the cutters and adapted to move the cutters up on the tongue.

6. In an underreamer, the combination of a mandrel having a downwardly projecting tongue with opposite outward bearing faces and with opposite inward bearing faces, cutters vertically movable on the tongue, said cutters being recessed on their inner faces, having spreading surfaces at the back of their recesses bearing against the outward faces of tongue, and having rentrant surfaces bearing on the inward faces of the tongue, the cutters substantially entirely surrounding the tongue, and means to hold the cutters intheir upper positions on the tongue.

7. ln an underreamer, the combination of a mandrel having a downwardly projecting tongue with ,substantially parallel opposite outward bearing faces and substantially parallel opposite inward bearing faces formed on the inner sides of overhanging edge parts of thevtongue, cutters vertically movable on the tongue, being recessed on their inner faces, having spreading surfaces at the back of their recesses and having` reentrant surfaces bearing on the inward faces of the tongue, and means to hold the cutters in their upper positions on the tongue.

8. In an underreamer, the combination of a mandrel having a downwardly projecting tongue with substantially parallel opposite outward bearing faces and substantially parallel opposite inward bearing faces formed on the inner sides of overhanging edge parts of the tongue, cutters vertically movable `on the tongue, being recessed on their inner faces, having spreading surfaces at the baclrof their recesses and having reentrant surfaces bearing on the inward faces of the tongue, the cutters substantially entirely surrounding the tongue, and means to hold the cutters iu their upper positions on the tongue.

9. ln an underreamer, the combination of a mandrel having a downwardly projecting tongue, a downwardly facing shoulder at the lower end of the mandrel at the upper end of the tongue, and a downwardly facing shoulder at the lower end of the tongue; vertically movable recessed cutters surrounding the tongue each having an upwardly facing surface at the lower end of its recess adapted tobear upwardly against the shoulder at the lower end of the tongue when the upper ends of the cutters bear against the shoulder-at the upper end of the tongue; and means to hold the cutters in their upper positions on the tongue with the upper ends of the cutters against the mandrel shoulder.

10. ln an underreamer, the combination of a mandrel having a downwardly projecting tongue, and a downwardly facing shoulder at the upper end of the tongue; said tongue having outward substantially parallel vertical bearing faces, having inward substantially parallel vertical bearing faces formed on the inner surfaces of extending edge portions of the tongue, and having downwardly facing shoulders at its lower end; vertically movable recessed cutters surrounding the tonguey having spreading surfaces at the back of their recesses, rentrant surfaces at the sides of their recesses, and upwardly facing surfaces at the bottoms of their recesses adapted to bear upwardly against the lower shoulders on the tongue when the up per ends of the cutters bear against the shoulder at the upper end of the tongue; and means to hold the cutters in their upper positions on the tongue with the upper ends of the cutters against the mandrel shoulder.

l1. In an underreamer, the combination of a mandrel having a cutter carrying tongue having opposite outward parallel bearing faces and opposite inward parallel bearing faces, recessed cutters fitting around the tongue and each having parallel surfaces bearing against said faces of the tongue and a. receding surface at the back of the recess to cooperate with the tongue, and means to hold the cutters up on the tongue.

l2. In an iindeii'eameitlie combination of a cutter' carrying tongue having opposite outward vertical and parallel bearing faces vand having' opposite inward vertical and parallel bearing faces formed on the inner surfaces of overhanging edge portions of the tongue, and having downwardly facing shoulders at its lower end; vertically movable recessed cutters fitting around the tongue having surfaces in the recesses bearing against said outward and inward bearing faces and said lower shoulder of the tongue, and means to hold the cutters up on the tongue.

13. In an underreamer, the combination of a mandrel having a cutter carrying tongue having` opposite outward vertical and parallel bearing faces and having opposite inward vertical and parallel bearing faces formed on the inner surfaces of overhanging edge portions of the tongue, and having downwardly facing shoulders at its lower end; and vertically movable recessed cutters fitting substantially entirely around the tongue, said cutters having spreading surfaces at the back sides of their recesses adapted to bear against the outward faces of the tongue, having rentrant surfaces adapted to bear against the inward faces of said tongue, and having upwardly facing surfaces at the bottoms of the recesses adapted to bear upwardly against the shoulders at the lower end of the tongue and means to hold the cutters up on the tongue.

ll. In an underreamer, the combination of a mandrel having a cutter carrying tongue having opposite outward vertical and parallel bearing faces and having opposite in- Award vertical and parallel bearing faces formed on the inner surfaces of overhanging edge portions of the tongue, and having downwardly facing shoulders at its lower end; vertically movable recessed cutters lit- Cil substantially entirely around the tongue, said cutters each having a recess open at the top and at the inner face of the slip, the back surface of the recess being formed into an upper vertical surface, an intermediate downwardly and outwardly receding surface, and a lower vertical surface in the plane of the upper vertical surface, the bottom of said recess being horizontal to bear upwardly against the lower shoulder on the tongue, and said recess having reentrant surfaces extending vertically from the bottom of the recess up to points opposite the lower edge of the first mentioned vertical surface of the back of the recess and from those points upwardly receding from the back of the recess and means to hold the cutters up on the tongue.

15. In an underreamer, the combination of a cutter carrying tongue having outward bearing surfaces, a lower extension with outward bearing surfaces, and a horizontalY shoulder between the outward bearing surfaces; and cutters vertically movable on the tongue, being recessed to fit around the tongue, having each a spreading surface at the back of the recess to bear against the outward tongue surfaces, a horizontal surface at the bottom of the recess to bear against the horizontal shoulder of the tongue, and a spreading surface below the horizontal surface to bear against the outward surface of the tongue extension and means to hold the cutters up on the tongue.

16. In an underreamer, a cutter elongated in form with a lower cutting end having a recess open on the inner and upper faces of the cutter, the back wall of said recess having a downward and outwardly receding surface and a lower vertical surface, and said recess having rentrant front walls with front surfaces facing the back wall, and having an upwardly facing bottom surface.

17. In an underreamer, a cutter elongated in form with a lower cutting end, having a recess open on the inner and upper faces of the cutter, the back wall ,of said recess having an upper vertical surface, an intermediate downwardly and outwardly receding surface, and a lower vertical surface in the plane of the upper vertical surface, the bottom wall of the recess being horizontal, and said recess hav-ing` rentrant front walls with inwardly facing surfaces facing the back surfaces, said inwardly facing surfaces extending vertically from the bottom surface to points opposite the lower edge of the upper back vertical surface and then extending upwardly reeedingly from the back surface.

18. In an underreamer. the combination of a mandrel with a lower tongue, vertically movable cutters substantially entirely surrounding the tongue, and cutter elevating means in the mandrel exterior of the tongue and connecting with the cutters outside the tongue.

19. In an underreamer, the combination of a mandrel having a solid downwardly projecting tongue of less size than the mandrel, vertically movable cutters around the tongue, and cutter elevating means in the mandrel exterior of the tongue and connecting with the cutters exterior of the tongue. y

20. In an underreamer, the combination of a mandrel having a solid downwardly projecting tongue of a less size than the mandrel, vertically movable cutters around the tongue, and spring actuated bolts in vertical bores in the mandrel entirely cxterior of the tongue, said bolts connecting at their lower ends with the cutters at their upper ends exterior of the tongue.

21. In an underreamer, the combination of a mandrel having a solid downwardly projecting tongue of less size than the mandrel, vertically movable cutters around the tongue, said cutters entirely surrounding the tongue at their upper ends, and spring actuated bolts of the same number as the number of cutters working in vertical bores in the mandrel over the meeting points of the cutters around the tongue, said bolts being outside the tongue, and connection between each bolt and the two cutters at their meeting points around the tongue, said bolts being outside the tongue.

22. In an underreamer, the combination of a mandrel having a downwardly projecting tongue with opposite outwardly facing bearing faces and with opposite inwardly facing bearing faces formed by the inner surfaces of overhanging edge portions of the tongue, cutters vertically movable on the tongue substantially entirely surrounding the same and having spreading surfaces adapted to bear against the outward faces of the tongue and having rentrant out` wardly facing surfaces bearing against the inward faces of the tongue, said cutters entirely surrounding the tongue at their upper ends, spring actuated bolts of the same number as the number of cutters working in vertical bores in the mandrel over the meeting points of the cutters around the tongue, said bolts being outside the tongue, and connection between each bolt and the two cutters meeting beneath it.

23. In an underreamer, the combination of a mandrel having a downwardly projecting tongue, cutters vertically movable on the tongue, said cutters being recessed on their inner faces to fit around the tongue and the cutters collectively substantially entirely surrounding the tongue, and entirely surrounding the tongue at their upper ends, spring actuated bolts of the same number as the number of cutters working in vertical bores in the mandrel over the meeting points ici Ici

CII

between each bolt and the two cutters meet-- ing beneath it.

24. ln an underreamer, the combination of a mandrel having a downwardly projecting tongue with opposite outward bearing faces and with opposite inward bearing faces, cutters vertically movable on the tongue, said cutters being recessed on their inner faces, having spreading surfaces at the back of their recesses bearing against the outward faces of the tongue, and having reentrant surfaces bearing on the inward faces of the tongue, the cutters substantially entirely surrounding the tongue, and entirely surrounding the tongue at their upper ends, spring actuated bolts of the same number as the number of cutters working in vertical bores in the mandrel over the meeting points of the cutters around the tongue, said bolts being outside the tongue, and connection.

between each bolt and the two cutters meeting beneath it.

25. ln an underreamer, the combination of a mandrel having a downwardly projecting tongue with substantially parallel opposite outward bearing faces and substantially parallel opposite inward bearing faces formed on the inner sides of overhanging edge parts of the tongue, cutters vertically movable on the tongue, being recessed on their inner faces, having spreading surfaces at the back of their recesses and having reentrant surfaces bearing on the inward faces of the tongue, said cutters entirely surrounding the tongue at their upper' ends, spring actuated bolts of the same number as the number of cutters working in vertical bores in the mandrel over the meeting points of the cutters around the tongue, said bolts -being outside the tongue, and connection the shoulder at the lower end of the tongue when the upper end of the cutter bears against the shoulder at the upper end of the tongue, said cutters entirely surrounding the tongue at their upper ends, spring actuated bolts of the same number as the number of cutters working in vertical bores in the mandrel over the meeting points of the cutters around the tongue, said bolts being outside the tongue and connection between each bolt and the two cutters meeting beneath it.

Q7. In an underreamer, the combination of a mandrel having a downwardly projecting tongue, and a downwardly facing shoulder at the upper end of the tongue; said tongue having outward substantially parallel vertical bearing faces, having inward substantially parallel vertical bearing faces formed on the inner surfaces of extending edge portions of the tongue, and having downwardly facing shoulders at its lower end; vertically movable recessed cutters surrounding the tongue having spreading surfaces at the back of the recesses, rentrant surfaces at the sides o-f their recesses, and upwardly facing surfaces at the bottoms of their recesses adapted to bear upwardly against the lower shoulders on the tongue when the upper ends of the cutters bear against the shoulder at the upper end of the tongue, said cutters entirely surrounding the tongue at their upper ends, spring actuated bolts of the same number as the number of slips working in vertical bores in the mandrel over the meeting points of the cutters around the tongue, said bolts being outside the tongue, and connection between each bolt and the two cutters meeting beneath it.

28. In an underreamer, the combination of a mandrel having a vertical bore, a vertically movable cutter, a bolt connected at its lower end with the cutter and extending up into the mandrel bore, a spring surrounding the bolt, a supporting sleeve for the lower end of the spring fitting around the bolt and into the bore, an enlargement on the bolt below the sleeve, and a wedge key adapted to be driven transversely across the mandrel beneath the spring supporting sleeve to raise the sleeve off the bolt enlargement.

29. In an underreamer, the combination of a mandrel having a vertical bore, a vertically movable cutter, a bolt connected at its lower end with the cutter and extending up into the mandrel bore, a spring surrounding the bolt, a supporting sleeve for the lower end of the spring fitting around the bolt and into the bore, an enlargement on the bolt below the sleeve, and a wedge key adapted to be driven transversely across the mandrel beneath the spring supporting sleeve to raise the sleeve off the bolt enlargement, said wedge key having a notch adapted to be entered by the sleeve when the lrey has fully entered to hold the key from displacement.

30. In an underreamer, the combination of a mandrel having a pair of vertical bores, vertically movable cutters, bolts connected at their lower ends to said cutters and eX- tending up into the mandrel bores, a spring surrounding each bolt, a supporting sleeve for the lower end of each spring fitting around the bolt and into the bore, enlargements on the bolts below the sleeves, the

mandrel having a cross opening lying adjacent each bore, and a single wedge key adapted to be driven transversely through said cross opening beneath the spring supporting sleeves to raise said sleeves off the bolt enlargements, said kwedge key being notched for entry of the sleeves to hold the key from displacement.

31. In an underreamer, the combination of a mandrel having a cutter carrying tongue having vertical outward bearing surfaces and having inward bearing surfaces extending vertically along the sides of the tongue and horizontally across its bottom, and recessed cutters fitting around the tongue having surfaces at the backs of the recesses bearing against the outward faces of the tongue and having rentrant surfaces formed on overhanging front walls at the sides and bottoms of the recesses, said rentrant surfaces adapted to bear against the inward bearing faces of the tongue, and means for holding the cutters up on the tongue.

32. In an underreamer, the combination of a mandrel having a cutter carrying tongue having vertical outward bearing surfaces and having inward bearing surfaces extending vertically along the sides of the tongue and horizontally across its bottom, and recessed cutters fitting around the tongue having surfaces at the backs of the recesses bearing against the outward faces of the tongue and having rentrant surfaces formed on overhanging front walls at the sides and bottoms of the recesses, said reentrant surfaces adapted to bear against the inward bearing faces of the tongue, the bottom of the tongue and the bottoms of the recesses being straight from side to side, and means for holding the cutters up on the tongue.

38. In an underreamer, the combination of a mandrel having a cutter carrying tongue having outward bearing faces, the lower end of the tongue being straight from side to side, overhanging edge portions extending along the edges of the outward bearing faces and extending straight across the bottom of the tongue from side to side; recessed cutters adapted to fit around the tongue, the bottoms of the recesses being straight from side to side, and the recesses having front walls on their sides and extending across their bottoms forming continuous rentrant surfaces facing the backs of the recesses and extending continuously along the sides of the recesses and straight across their bottoms, and means for holding the cutters up on the tongue.

34. In an underreamer, the combination of a mandrel with a downwardly projecting parallel-sided tongue, recessed cutters, vertically movable on and exterior of the tongue, the recesses of the cutters having f downwardly and outwardly receding surfaces to cooperate with the parallel sides of the tongue, and elevating means to move the cutters up on the tongue.

35. In an underreamer, the combination of a mandrel with a downwardly projecting parallel sided tongue, recessed cutters vertically movable on and surrounding the tongue, the recesses of the cutters having vertical back surfaces and downwardly and outwardly receding surfaces to coperate with the parallel sides of the tongue, and elevating means to move the cutters up on the tongue.

36. In an underreamer, the combination of a mandrel with a downwardly projecting tongue, recessed cutters vertically movable on and surrounding the tongue, the recesses of the cutters having back surfaces adapted to bear against the tongue when the cutters are elevated thereon and having back surfaces receding downwardly and outwardly to allow the cutters to contract when lowered on the tongue, and means to hold the cutters up on the tongue.

37. In an underreamer, the combination of a mandrel with a downwardly projecting tongue having downwardly facing shoulders at its lower end, recessed cutters vertically movable on and surro-unding the tongue, the recesses having upwardly facing bottom surfaces adapted to bear upwardly against the downwardly facing shoulders of the tongue when the cutters are in upper position on the tongue, and means to hold the cutters up on the tongue.

88. In an underreamer, the combination of a mandrel with a downwardly projecting tongue having downwardly facing shoulders at its lower end, recessed cutters vertically movable on and surrounding the tongue, the recesses having upwardly facing bottom surfaces adapted to bear upwardly against the downwardly facing shoulders of the tongue, and means to hold the critters up on the tongue, the tongue having outwardly projecting ledges extending along its vertical edges and across its lower end, and the cutter recesses having coperating rentrant surfaces extending along their opposite sides and across their bottoms.

39. In an underreamer, the combination of a mandrel with a downwardly projecting parallel-sided tongue having downwardly facing shoulders at its lower end, recessed cutters vertically movable on and surrounding the tongue, the recesses having downwardly and outwardly receding back surfaces to cooperate with the parallel faces of the tongue and having upwardly facing bottom surfaces adapted to bear upwardly against the downwardly facing shoulders of the tongue, and means to hold the cutters up on the tongue.

40. In an underreamer, the combination llo .lill

of a mandrel with a downwardly projecting parallel-sided tongue having' downwardly facing shoulders at its lower end, recessed cutters vertically movable on and surrounding the tongue, the recesses having downwardly and outwardly receding back surfaces to coperate with the parallel faces of the tongue and having upwardly facing bottom surfaces adapted te bear upwardly against the deunwardly facing shoulders of the tongue, and means to lhold the cutters up on the tongue, the tongue having outwardly projecting ledges extending along its vertical edges and across its lower end, and the cutter recesses having cooperating rentrant surfaces extending along their opposite sides and across their bottoms.

4l. In an underreamer, the combination of a mane rel having a downwardly projecting tongue with outward bearing faces and inward bearing faces, cutters recessed to fit around the tongue and having surfaces bearing against said outward and inward bearing faces thereof, and means to hold the cutters up'on the tongue.

a2. in an underreamer, the combination of a mandrel havinga downwardly projecting tongue with outward bearing faces and inward bearing faces, recessed cutters on the tongue with surfaces bearing against said outward bearing faces of the tongue and with reentrant surfaces bearing against the inward bearing faces of the tongue, and means to hold the cutters up on the tongue.

a3. ln an underreamer, the combination of a mandrel having a downwardly projecting tongue with outward bearing faces and inward bearing faces, along its vertical sides and across its bottom, recessed cutters on the v tongue with surfaces bearing against said outward bearing faces of the tongue and with rentrant surfaces bearing against the inward bearing faces of the tongue, said rentrant surfaces extending along the sides of the recesses and across their bottoms, and means to hold the cutters up on the tongue.

4A. ln an underreamer, a cutter elongated in form with a lower cutting end, having a recess open on the inner and upper faces of the cutter, the back wall of said recess having a downward and outwardly receding surface and a lower 'vertical surface, and said recess having rentrant front .walls with front surfaces facing the back wall, and having an upwardly facing bottom surface, the rentrant front wall extending along the sides of the recess and across its bottom.

e5. ln an nnderreamer, the combination of a mandrel with downwardly projecting tongue, cutters fitting around the tongue, and elevating means exterior of the tongue connecting with the cutters and adapted to move the cutters up on the tongue.

a6. ln an underreamer, the combination of a mandrel with a downwardly projecting tongue, vertically movable cutters fitting around the tongue, and cutter elevating means comprising bolts each connected at their lower ends with the cutters, a spring surrounding each bolt, and spring supporting means embodying a single supporting member common to and supporting all of the springs.

Lil-7. ln an underreamer, the combination of a mandrel with a downwardly projecting tongue, vertically movable cutters fitting around the tongue, and cutter elevating means comprising bolts each connected at their lower ends with the cutters, a spring surrounding each-bolt, and spring raising and supporting means embodying a wedge key common to all of the springs and adapted to be driven under the springs to raise and support them.

48. ln an iuide'rreamer, the combination of a mandrel with a cutter carrying tongue, cutters vertically movable on the tongue, and

itter supporting means of the same number as the number of cutters and each connecting with two cutters.

In an underreamer, the combination lof a mandrel with a cutter carrying tongue, cutters fitting around the tongue and vertically movable thereon, and cutter supporting means of the same number as the number of cutters and each connecting with two adjacent cutters exterior of the tongue.

50. ln an underreamer, the combination of a mandrel having a vertical bore, a vertically movable cutter, a bolt connected at its lower end with the cutter and extending up into the mandrel bore, a spring surrounding the bolt, a supporting sleeve for the spring fitting around the bolt and into the bore, means in connection with the bolt for ini tially supporting the sleeve, and wedge means supported by the mandrel and adapted to lift the sleeve off its initial supporting means and to permanently support the sleeve.

51. ln an underreamer, the combination of a mandrel with a cutter carrying tongue, a recessed cutter fitting around the tongue and vertically movable thereon, and elevating means in the mandrel exterior of the tongue connecting with the cutter exterior of the tongue and adapted to move the cutter up on the tongue.

52. ln an underrcamer, the combination of a mandrel with a cutter carrying tongue having a downwardly facing shoulder at its lower end, a recessedv cutter fitting around the tongue and vertically movable thereon, the lower end of the cutter recess having an upwardly facing surface adapted to coperate with the tongue shoulder when the cutter is in upper position, and means to hold the cutter up on the tongue.

53. ln an underrcamer, the combination of fizO a mandrel with a cutter carryingtongue having .an outward bearing surface and an inward bear-ing surface,k YaY-recessed cutter fitting -artmnd the tongue, the cutter recess having rentrant front surfaces adapted to bear aga-inst the inward bearing surface of the tongue, and vmeans to hold the cutter up on tthe tongue.

54. In an underreamer, the combination of -a mandrel with a cutter carrying tongue hav-ing an outward hearing surface and an inward .bearing surface, a recessed cutter fitting around the tong-ue, the cutter recess having rentrant fro-ntsurfaces adapted to bear against the inward bearing surface of the tongue, and means to hold the cutter up on the tongue, said inward bearing surface of the tongue extending across the end of the ton-gue and said rentra-nt surfaces of the recess extending across the end of the recess.

55. In an underreame'r, the combination of a mandrel with a cutter carying ton-gue having a vertical outward bearing face and inward .bearing faces, 4a recessed cutter fitting around the tongue and vertically movable thereon, the cutter recess having ren- -trant front walls engaging the inward bearing faces of the cutter and a back surface of the recess receding' downwardly and outwar-dly, and means to hold the cutter up on lthe tongue. v

5.6. In an underreamer, the combination of a mandrel with a cutter carrying tongue, cutters surrounding the tongue, means provided in the cutters and tongue to cause eX- v pansion of the -cutters upon movement thereof nelative to 4:the tongue, and cutter moving 'means-,in the mandrel .eXteri or of the tongue connecting to the cutters exterior of the tongue.

57. In an underreamer, the combination of ,amandrel with a'downwardly proyecting tongue, cutters around the tonguel and vertically movable thereon, said cutters meeting each .other .in their upper parts and being cut away below to form on each cutter a .downwardly facing shoulder' below the surface where it meets ano-ther cutter, a stationary pin set transversely through the tongue :and projecting between the'cutters beneath their said should-ers, and means to hold the cutters up on the tongue.

e 58. In an underreamer, the combination of a mandrel with a downwardly .projecting tongue, cutters around the tongue and vertically movable thereon, said cutters and tongue having interengaging surfaces hold- .ing the cutters to the tongue and preventing their outward lateral displacement, said cutters meeting eachother in their upper parts V.and being 'cut away below to form on each .cutter a downwardly facing shoulder below Copies of this patent may he Aobtained for five cents each, by addressing the Washington, C."

the surface where it meets another cutter, la stationary pin set transversely through .the tongue and projecting between the cutters :beneath their said shoulders, and means to hold the cutters up on the tongue.

59. In an underreamer, the combination of a mandrel with a downwardly projecting parallel faced tongue substantially rectangular in cross-section, projecting ledges along the four vertical edges of the tongue forming inwardly facing bearing surfaces, a pair of recessed cutters situated oppositely on and surround-ing the tongue and vertically movable thereon, having rentrant recess surfaces bearing on the inwardly facing surfaces of the tongue, the cut-ters surrounding the tongue in their lupper portions and meeting .each other on 4a vertical plane central of the tongue, and the cutters being each cut away below to form downwardly facing shoulders below the portions which moet, a stationary pin set transversely through the tongue in said central vertical plane, and means to hold the cutters up on the tongue.

60. In an underreamer, the combination of a mandrel with a downwardly projecting tongue, cutters vertically movable on the tongue, cooperating surfaces on the cutters and tongue causing expansion of the cutters when moved upwardly and allowing contraction when moved downwardly, the cutters meeting ea-ch other in their upper parts and having meeting surfaces which meet when the -cutters are expanded and having also other meeting surfaces directly below the first mentioned meeting surfaces which meet when the cutters are contracted, each `of the cutters being cut away to form downwardly facingshoulders at the lower ends of the last mentioned meeting surfaces, a Stationary pi-n -set transversely through the tongue below the said shoulders, and means to hold the cutters up on :the tongue.

6l; In an underreamer, the combination of a mandrel having a vertical bore, a vertically movable cutter, a bolt connected at its lower end to the cutter and extending up into the bore with a head on its upper end, a-spring surrounding the bolt and bearing upwardly against the bolt head, means ou the bolt for initially supporting the lower end of the spring, and wedge means in the mandrel adapted to lift .the lower end of the spring olf its initial supporting means and to permanently support the spring in the mandrel.

In witness that I 4claim the foregoing I have hereunto subscribed my name this 28rd day .of August, 1916.

EDWARD L. MILLS.

Witness:

ELwooD I-I. BARKELEW.

Commissioner of Patents. 

